A multi Wide Area Network (WAN) Site-to-Site VPN router is a router that supports aggregating the bandwidth of multiple interconnections, e.g., WAN connections for accessing one or more remote private networks. In some implementations, each TCP/IP session is routed to only one WAN. In this configuration, a single TCP file transfer session can only utilize the bandwidth of one WAN connection on each end. For example, in a session based site-to-site virtual private network (VPN) connection VPN traffic is routed to multiple WAN connections between two sites (e.g., sites A and B).
In one implementation, M×N tunnels are initially formed between the WAN connections where M and N are the number of WAN network connections of site A and site B, respectively. Application TCP/IP sessions are then routed over the different tunnels. It is notable, however, that while a session based site-to-site VPN is able to utilize different tunnels for different sessions, a single download session in this type of connection is only able to utilize one tunnel.
In order to increase throughput of single data transfer sessions, routing schemes have been created in an attempt to utilize multiple WAN connections for a single TCP/IP session. In some cases channel bonding is implemented. For example, in bonded site-to-site VPN connections on multi WAN routers, data from a single TCP/IP session is distributed to multiple tunnels. In these arrangements, the M×N tunnels are utilized according to their respective uplink or downlink bandwidth, and the amount of data in a single session that is sent over these tunnels is distributed in proportion to the individual bandwidth ratios of the tunnels. These solutions, however, still fail to take into the account that some tunnels should not be used for transmitting data because of one or more conditions. Furthermore, these solutions also do not take into account that some network interfaces fail to satisfy one or more conditions, and thus those network interfaces should not be used for transmitting data.